4.1 KiB
haskell.nix
is infrastructure for building Haskell packages with Nix
haskell.nix
can automatically translate your Cabal or Stack project and
its dependencies into Nix code.
Documentation
Getting started
a) Using cabal.project
Add a default.nix
:
let
# Fetch the latest haskell.nix and import its default.nix
haskellNix = import (builtins.fetchTarball https://github.com/input-output-hk/haskell.nix/archive/master.tar.gz) {};
# haskell.nix provides access to the nixpkgs pins which are used by our CI, hence
# you will be more likely to get cache hits when using these.
# But you can also just use your own, e.g. '<nixpkgs>'
nixpkgsSrc = haskellNix.sources.nixpkgs-2003;
# haskell.nix provides some arguments to be passed to nixpkgs, including some patches
# and also the haskell.nix functionality itself as an overlay.
nixpkgsArgs = haskellNix.nixpkgsArgs;
in
{ pkgs ? import nixpkgsSrc nixpkgsArgs
, haskellCompiler ? "ghc865"
}:
# 'cabalProject' generates a package set based on a cabal.project (and the corresponding .cabal files)
pkgs.haskell-nix.cabalProject {
# 'cleanGit' cleans a source directory based on the files known by git
src = pkgs.haskell-nix.haskellLib.cleanGit { name = "haskell-nix-project"; src = ./.; };
compiler-nix-name = haskellCompiler;
}
Note that you'll need to add a comment specifying the expected sha256
output for your source-repository-packages
in your cabal.project
file:
source-repository-package
type: git
location: https://github.com/input-output-hk/iohk-monitoring-framework
subdir: plugins/backend-editor
tag: 4956b32f039579a0e7e4fd10793f65b4c77d9044
--sha256: 03lyb2m4i6p7rpjqarnhsx21nx48fwk6rzsrx15k6274a4bv0pix
b) Using stack.yaml
Add a default.nix
:
let
haskellNix = import (builtins.fetchTarball https://github.com/input-output-hk/haskell.nix/archive/master.tar.gz) {};
nixpkgsSrc = haskellNix.sources.nixpkgs-2003;
nixpkgsArgs = haskellNix.nixpkgsArgs;
in
{ pkgs ? import nixpkgsSrc nixpkgsArgs
}:
pkgs.haskell-nix.stackProject {
src = pkgs.haskell-nix.haskellLib.cleanGit { src = ./.; };
}
Working with a project
To build the library component of a package in the project run:
nix build -f . your-package-name.components.library
To build an executable:
nix build -f . your-package-name.components.exes.your-exe-name
To open a shell for use with cabal
run:
nix-shell -A shellFor
cabal new-build your-package-name
cabal new-repl your-package-name:library:your-package-name
Using a binary cache
To use precompiled binaries you'll need:
- To configure the IOHK binary cache by following the instructions on iohk.cachix.org.
- To pin your
nixpkgs
to match one of the revisions built by our CI: these can be found inside thesources
attribute (see the quickstart above for an example).
Related repos
The haskell.nix
repository contains the runtime system for building
Haskell packages in Nix. It depends on other repos, which are:
-
nix-tools
— provides the programs for generating Nix expressions from Haskell projects. -
hackage.nix
— the latest contents of the Hackage databases, converted to Nix expressions. -
stackage.nix
— all of the Stackage snapshots, converted to Nix expressions.
IRC Channel
Join the #haskell.nix channel on irc.freenode.net to get help or discuss
the development of haskell.nix
and nix-tools
.